wfsfilteraux: Auxiliary functions to create filters

In HanOostdijk/HOQCwfs: Web Feature Service (WFS) read-only interface

Auxiliary functions to create filters

Description

• The function build_filter creates a filter for the indicated version by inserting the appropriate 'xmlns' urls in the Filter tag and inserting the XML elements from the ... argument i.e. all arguments except version and sep. While evaluating these elements the version and separator are temporarily set to the arguments version and sep of build_filter unless explicitly overwritten.

• The function propeq_xml creates a PropertyIsEqualTo XML clause

• The function propertyname_xml creates a PropertyName or ValueReference XML clause

• The function bbox_xml creates a BBOX XML clause

Usage

build_filter(..., version = WFS_get_version(), sep = WFS_get_sep())

propertyname_xml(propname, version, nopref = T)

propeq_xml(propname, propvalue, version = WFS_get_version())

bbox_xml(gemprop, crs_in, coords, version = WFS_get_version())

Arguments

...	XML elements to be added to filter
version	Character string with the WFS request version
sep	NULL for the default separator (set by WFS_set_sep()) or required separator otherwise
propname	Character string with the PropertyName (1.1.0) or ValueReference (2.0.0)
nopref	Logical scalar indicating the 'ogc:' pref is not to be used in propertyname_xml
propvalue	Character string to filter with
gemprop	Character string with the name of the geometric field
crs_in	Character string with the name of the input crs (e.g. "EPSG:4326" )
coords	Numeric vector with four elements indicating the bounding box

Value

Character vector with the created filter or xml fragment.

Examples

bbox_28992 <- c(119103, 480726, 119160, 481078)
f1 <- build_filter(version='1.1.0',
   fg("And"
       , propeq_xml('topp:boom_omschrijf',"Alnus glutinosa 'Laciniata'")
       , bbox_xml("geometrie","EPSG:28992",bbox_28992)
     )
  )
bbox_4326 <- convert_bbox(bbox_28992,"EPSG:28992","EPSG:4326")
f2 <- build_filter(version='2.0.0',
   fg("And"
       , propeq_xml('topp:boom_omschrijf',"Alnus glutinosa 'Laciniata'")
       , bbox_xml("geometrie","EPSG:4326",bbox_4326)
     )
  )
pn_construct <- propertyname_xml('han','2.0.0',nopref =F)

HanOostdijk/HOQCwfs documentation built on March 6, 2023, 8:18 a.m.